Under-Chainstay U-Brake Solution?

[Wolfgang Weiss]

Measure the crown race. ......easiest way.

Iso is standard size....26.4mm

Jis is 27.0mm

Crib sheet here

https://www.sheldonbrown.com/cribsheet-headsets.html
Unless its old old old french, its unlikely to be french size..

I don't have caliber so I cannot measure it.

 

[legrandefromage]

May I ask you a question? I bought this frame without a headset and since it's french brand I have a suspicion - it fits french headset or ISO?

Standard threading

 

[Tootyred]

Add it to your Christmas list....cheap analogue(not cheap digital) they are a vital part of pretty much any tool kit, especially if your going to be messing about with stuff like this! £14

https://www.screwfix.com/p/magnusso...VxOvtCh3c5w6jEAQYAiABEgIC9fD_BwE&gclsrc=aw.ds
Or similar.

If your really want to spash out buy a moore and wright pair......for £18

https://www.machine-dro.co.uk/moore...MIjr7chKj2-gIVBe_tCh0gkQAGEAQYAiABEgITAfD_BwE
No batteries, more accurate as the scale never slips (which it will on cheap digital ones). Be with you for the rest of your life!

 

[legrandefromage]

Here you go

 

[elite504]

Cams for sensible money in the UK.
Considering how much in the firing line for mud an under chainstay brake is, going NOS eliminates the potential for worn bushes and a perpetually squeaky brake

https://bicyclist.cc/?s=roller+cam&post_type=product

 

[MuchAlohaNui]

I don't have caliber so I cannot measure it.

Take piece of paper
Precisely wrap around crown race mating surface
Paper edge seated on race surface
Mark overlap w/ sharp pencil
Remove paper
Lay flat
Use ruler with mm
Measure end of paper to pencil line
Divide by 3.14
D = C/pi
All measurements are to three significant figures anyhow
Do this paper thing three times for spatial resolution

 

[Tootyred]

Or just blow £13 .